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  <title>Document</title>
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  <script>
    let str = 'index_abcde'
    // 经过处理 return 出 indexAbcde
    // console.log(str.indexOf('_'));
    let a = 
    str = str.slice(0,str.indexOf('_')) + str.slice(str.indexOf('_')+1,str.length).slice(0,1).toUpperCase() + str.slice(str.indexOf('_')+1,str.length).slice(1,str.slice(str.indexOf('_')+1,str.length).length)
    console.log(str);
  </script>
</body>
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